
assume cs:code, ds:data
data segment
	db "Beginner's All-purpose Symbolic Instruction Code.", 0
data ends


code segment
start:	mov ax, data
		mov ds, ax
		mov si, 0

		call myfun1
		mov ax, 4c00h
		int 21h	


myfun1:	push si
		
s:		cmp byte ptr [si], 0
		je q
		cmp byte ptr [si], 61h ;61h是a的ascii码
		jb s1
		cmp byte ptr [si], 7Ah ;7Ah是z的ascii码
		ja s1
		and byte ptr [si], 11011111b
s1:		inc si
		jmp short s

q:		pop si
		ret



code ends

end start

